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Nel was shown to be alive in chapter 485 as she went to the Human World to alert Ichigo to a problem in Hueco Mundo.

Prior to that, Nel was last seen in volume 39's end of chapter sketches (in the wake of Nnoitra's defeat but before Zaraki went to fight Yammy) with Kenpachi in the same general area where Ichigo/Grimmjow/Nnoitra/Zaraki all fought. She was dreaming about Dondochakka & Pesche fighting, woke up to see Kenpachi, thought he was a monster closed her eyes and hoped she was dreaming then opened them again. Kenpachi realizes that she is alive and says he'll hit her to wake her up and Nel calls out for Ichigo.